How setup MTA/SMTP server as post master

[satimis]

Hi folks,


I have been googling around for a Howto/Guide/Tutorial to setup a MTA/SMTP server to route incoming mails to their respective server based on domain. It brought many threads and I hesitate which is the right direction to proceed.


My goal is;

All domains points to the same fixed/external IP.

Several Mail Servers running on a Virtual Box


Guest_1, the SMTP server do the routing (using the DNS with the MX records)

Internet (incoming mails) -> via router forwarding port 25 -> Guest_1 - smtp server -> decides to send mails to Guest_2, Guset_3, Guest_4, Guest_5. etc. based on domain.


Please shed me some light. TIA


B.R.
satimis

[centuser1]

There are quite a few people on here who do some good mail stuff.

I think you might want to be more specific.

Have you decided on which mail software you are going to use? Exim, postfix, sendmail, other?
Once you get that out of the way, post a little example of what you are doing, you can use fake site names.

For instance...I would gather you have a router between you and the net that you seem to have some control over. You want a server to act as an incoming (and probably outgoing?) email server for all your domains?

You have many servers with different domains on them and want that one server to forward mail once received to its proper place?
You want that server to also receive mail from your servers (relay) and then push them to the internet?

DO you control your dns on your own servers, at the datacenter, or some third party out there somewhere?

Someone will point you in the right direction if you can answer and tell as much as you can about your particular scenario.

[satimis]

Hi centuser1,


Thanks for your response.


This is a test. What I'm prepared to test is as follows;

On a Virtual Box there are many mail servers running, each allotted with an local IP.

Host - headless base server without running any application

Guests - headless mail server


The Guests can be accessed remotely either on the Host or on other workstations on the LAN. They are working nicely now.


If running a range/bundle of external/fixed IP. All Guests can work as separate Mail Server box.

Have you decided on which mail software you are going to use? Exim, postfix, sendmail, other?

Postfix.

Once you get that out of the way, post a little example of what you are doing, you can use fake site names.

For instance...I would gather you have a router between you and the net that you seem to have some control over. You want a server to act as an incoming (and probably outgoing?) email server for all your domains?

Similar to Virtual Domain. For Web Server if all domains point to the same external/fixed IP it works without problem. It will direct the request to the respective Web Server. But for Mail Servers all of them need port 25.

You have many servers with different domains on them and want that one server to forward mail once received to its proper place?
You want that server to also receive mail from your servers (relay) and then push them to the internet?

Yes.

Connection;

ISP -> DSL Modem -> Router -> Virtual Machine -> SMTP server (Guest_1) -> Mail Servers, Guest_, _2, _3, etc.

The SMTP server only route the mails from/to Internet.


The Router is suppled by ISP. I can't touch it. The LAN is also shared with other workstations. If without workstations, the connection can be;

ISP -> DSL Modem -> Virtual Machine -> SMTP server (Guest_1) -> Mail Servers, Guest_, _2, _3, etc.

DO you control your dns on your own servers, at the datacenter, or some third party out there somewhere?

I suppose I have to build an internal DNS server for the job. ISP's DNS server can't work because all domains point to the same external IP.


B.R.
satimis